The invention relates to shower heads and, in particular, to a type of spray head in which a flow regulator is provided to maintain a fluid flow rate within preset limits regardless of variations in supply pressure and operating temperatures.
A typical shower head produces a conical spray pattern of water. It produces this effect by causing water from the supply line to be directed through a plurality of orifices, each substantially smaller than the size of the supply line. These orifices subdivide the flow into fine streams of water and further serve to spread the flow of water over a larger area.
The rate of flow through a typical shower head is dependent upon numerous factors, including the supply line pressure. Generally, the supply line pressure will vary among installation sights and also will vary during the course of a day at a given installation site. The effectiveness of the spray pattern as well as the water flow rate will vary with the supply line pressure. Common shower heads have a fixed outlet size and are designed to provide adequate shower operation at average pressures and at average water flow rates. Such shower heads are not suitable for installation in applications where extreme pressure variation occurs.
In installations where water conservation is of concern, a shower head capable of maintaining a water flow rate within certain limits regardless of supply line pressure is necessary. A military ship is an example of such an installation because it has a limited supply of water which makes water conservation an absolute necessity. For this reason, shower heads for use on military ships must meet certain military specifications, specifically MIL-S-955C. This specification requires that a shower head provide a constant flow rate within specified limits and over a range of operating temperatures and a range of supply pressures.
Shower heads have been proposed in the past which were intended to meet this specification but none has proved consistantly successful. These proposals would employ devices intended to regulate and maintain a constant flow rate under varying pressure conditions. One proposed system would employ an elastomeric flow control element which included an aperture, the size of which was intended to vary depending on the supply line pressure. This element was proposed to be interposed in the flow control path to act as a variable restriction. One problem encountered with this type of device, is that the properties of elastomeric materials vary with operating temperature and with age. Additionally, they can be quite difficult to manufacture consistently. Thus, although these elements theoretically should maintain a constant flow rate in a shower head, in operation they fail to do so because the physical properties of the material vary due to the operating environment and the manufacturing process itself.
A second problem associated with prior shower heads is cost. In many of these suggested shower heads, the flow regulating devices added significantly to the overall manufacturing cost. This coupled with marginal performance rendered these shower heads unsuitable for many applications.